This has discussed at length in other topics. Each observation records an encounter between an individual human observer and an organism. If there are ten humans present, then each of the ten observers can record observations with that one same organism. iNaturalist is, in this sense, a personal journaling of encountered organisms. Comments in the following topics make this rather clear.
https://forum.inaturalist.org/t/same-observation-multiple-observers/7463
https://forum.inaturalist.org/t/share-observations-between-users/337
https://forum.inaturalist.org/t/sharing-observations-and-annoying-useless-duplicate-comments/6087/4
One could use the observation fields to link the observations together, including a proposed way to link groups of observations
https://forum.inaturalist.org/t/link-observations/1367/4
Forgive me if I have misunderstood the issue!